Optical disc medium, recording method thereof and recorder

ABSTRACT

An optical disc medium, including a plurality of sector groups each being made up of multiple contiguous sectors on a track, is provided. In this optical disc medium, the location information of each of those sector groups is divided into a predetermined number of information pieces and distributed to associated sectors on the same track.

TECHNICAL FIELD

[0001] The present invention relates to a rewritable optical disc mediumand also relates to a recording method and recorder thereof.

BACKGROUND ART

[0002] In recent years, the optical disc has been used more and moreextensively to store video information thereon. Thus, to record a videoof even better quality thereon for a longer time, further increase inrecording density and read/write speeds thereof is strongly demanded. Toachieve this purpose, it is naturally effective to develop a novelstorage medium on which information can be stored at an even higherdensity. However, it is equally important and pressing as well to reducea so-called “overhead area” (e.g., address area), not contributing toincrease in the capacity of information to be stored, as much aspossible.

[0003]FIG. 13 illustrates a format for an information track on aconventional optical disc. In FIG. 13, the reference numeral 1501denotes a sector as an information unit, the reference numeral 1502denotes a non-rewritable header field recorded in the shape of pitswhile the optical disc is manufactured, and the reference numeral 1503denotes a recording field on which information can be written.

[0004] In the conventional optical disc, each track has a format inwhich a number of sectors 1501 are arranged in line as minimumread/write units. Each of these sectors 1501 consists of a header field1502 having a length of 128 bytes and a recording field 1503 having alength of 2,569 bytes.

[0005] Although not shown in FIG. 13, the recording field includes a VFO(variable frequency oscillator) field, a data field on which user datais written, and a buffer field as a redundancy area. The VFO field isprovided to accomplish a phase lock on a PLL (phase-locked loop), whichis needed for reading out a signal recorded.

[0006] In the conventional optical disc, to specify what sector on whatpart of the disc a light beam spot is now following, each header field1502 includes location information (i.e., address informationrepresenting a specific location on the optical disc). The locationinformation stored on the header field 1502 indicates the locationinformation of the sector 1501 including the header field. Morespecifically, as shown in FIG. 13, location information “123456” hasbeen recorded on the header field of the sector 1501 specified by anaddress “123456”. This location information has a length of 4 bytes. Anerror detection code of 2 bytes is added to the 4-byte locationinformation to see if the location information has been read outcorrectly.

[0007] A signal representing the location information is recorded at thesame density as the data to be written on the recording field.Accordingly, the signal, as well as the data, needs to be read out usinga PLL. For this purpose, a VFO field is also provided for the header.When an optical disc is used as a peripheral storage device for acomputer, the information stored on the optical disc should be much morereliable as compared to a situation where the same optical disc is usedto record or replay video or music on/from it. Thus, to consolidate thereliability, the same location information is recorded four times on asingle header. As a result, the location information per header has atotal length of 128 bytes.

[0008] As described above, in the conventional optical disc, each sectorhas to store the same location information thereon physically four timesand also needs a so-called “overhead area” such as a VFO field.Accordingly, the storage capacity of the optical disc decreasescorrespondingly.

[0009] In order to overcome the problems described above, the presentinvention was made and its object is to provide an optical disc thatincludes a smallest possible overhead area and can be used effectivelyto store video or any other type of information thereon, and an opticaldisc drive for such a disc.

DISCLOSURE OF INVENTION

[0010] An optical disc medium according to the present inventionincludes a plurality of sector groups, each being made up of multiplesectors that are contiguous with each other in a circumferentialdirection on a track. In at least some of the sector groups, thelocation information thereof is divided into multiple pieces ofinformation and distributed to associated ones of the sectors on thesame track.

[0011] The location information is preferably represented by a pluralityof identification marks that are formed as embossed pits. Also, eachsaid embossed pit is preferably formed between recording fields ofassociated ones of the sectors that are adjacent to each other in thecircumferential direction on the track.

[0012] In a preferred embodiment, each said sector group is made up of32 contiguous sectors.

[0013] In another preferred embodiment, each said identification markassumes one of three mutually different states and representssynchronization information or one-bit information of 1 or 0 by any ofthe three different states.

[0014] In another preferred embodiment, each said identification mark isprovided within a header gap that has a length of 200T or less in adirection in which the track extends, where T is a distance that a lightbeam goes in one reference clock period.

[0015] In another preferred embodiment, each said identification mark ismade up of at most two of the embossed pits. The identification marksmay be arranged on a centerline of the track on which information isrecorded. Alternatively, the identification marks may also be arrangedso as to be shifted by a half track pitch from the centerline of thetrack.

[0016] In another preferred embodiment, the optical disc medium has arecording plane that is divided into a plurality of band-like zonesarranged concentrically around the center of the disc medium. Multipletracks are included in each said zone. The number of sectors included ineach said track changes on a zone-by-zone basis. The number of sectorsincluded in each said zone is a multiple of the number of sectors thatmakes up each said sector group.

[0017] In another preferred embodiment, the location information of anarbitrary one of the sector groups is distributed to multiple sectorsincluded in the sector group.

[0018] In another preferred embodiment, the optical disc medium includesa non-usable dummy sector, and the identification mark included in thedummy sector is provided with invalidity information that makes thesector identifiable as the dummy sector. The invalidity information ispreferably identical with the synchronization information.

[0019] In another preferred embodiment, the number of sectors that makesup each said sector group is a multiple of the number of sectors thatmakes up a sector block on which logical processing is performed. Thesector located at the top of each said sector group is preferablyidentical with the sector located at the top of one of the sector blockson which the logical processing is performed. The logical processing maybe either error correction processing or interleaving processing.Replacement processing is preferably performed on a sector group basis.

[0020] In another preferred embodiment, each said sector has itslocation information recorded thereon.

[0021] In another preferred embodiment, the optical disc medium has arecording plane that is divided into a plurality of band-like zonesarranged concentrically around the center of the disc medium. Multipletracks are included in each said zone. The number of sectors included ineach said track changes on a zone-by-zone basis. In at least one of thezones, the number of sectors that makes up the zone is not a multiple ofthe number of sectors that makes up each said sector group. In thatcase, the sectors that make up the zone may include a remainder sectorthat does not belong to any of the sector groups, and the identificationmark of the remainder sector may be provided with information that makesthe sector identifiable as the remainder sector. No information ispreferably recorded on the recording field of the remainder sector.

[0022] An optical disc recording method according to the presentinvention is a method for performing recording on the optical discmedium according to any of the preferred embodiments described above. Inthis method, the replacement processing is performed on a sector groupbasis.

[0023] Another optical disc recording method according to the presentinvention is a method for recording information on the optical discmedium according to any of the preferred embodiments described above. Inthis method, each said sector has its own location information recordedthereon.

[0024] Still another optical disc recording method according to thepresent invention is a method for recording information on the opticaldisc medium including the remainder sector. In this method, theinformation is not recorded on the recording field of the remaindersector.

[0025] Yet another optical disc recording method according to thepresent invention is a method for recording information on the opticaldisc medium including the remainder sector. In this method, aninvalidity signal is recorded on the remainder sector.

[0026] An optical disc recorder according to the present invention is arecorder for performing recording on the optical disc medium accordingto any of the preferred embodiments described above. In this recorder,each said sector has its own location information recorded thereon.

[0027] Another optical disc recorder according to the present inventionis a recorder for recording information on the optical disc mediumincluding the remainder sector. In this recorder, the information is notrecorded on the recording field of the remainder sector. An invaliditysignal that makes the sector identifiable as the remainder sector ispreferably recorded on the recording field of the remainder sector.Alternatively, the invalidity signal may also be recorded on theremainder sector.

BRIEF DESCRIPTION OF DRAWINGS

[0028]FIG. 1 illustrates a format for an optical disc according to thepresent invention.

[0029]FIG. 2 shows a relationship between sectors and a sector group inthe optical disc of the present invention.

[0030] FIGS. 3(a) through 3(c) illustrate physical shapes of headerfields on the optical disc of the present invention.

[0031] FIGS. 4(a) through 4(d) illustrate exemplary arrangements ofidentification marks that may be used for the optical disc of thepresent invention.

[0032]FIG. 5 shows an exemplary arrangement of location information onthe optical disc of the present invention.

[0033] FIGS. 6(a) and 6(b) show a buffer track on the optical disc ofthe present invention.

[0034] FIGS. 7(a) and 7(b) show a relationship between sector groups andlogical processing blocks on the optical disc of the present invention.

[0035]FIG. 8 shows how replacement processing may be performed on theoptical disc of the present invention.

[0036]FIG. 9 shows the details of a sector on the optical disc of thepresent invention.

[0037]FIG. 10 shows the end of Zone No. 0 on the optical disc of thepresent invention.

[0038]FIG. 11 shows another exemplary arrangement of locationinformation on the optical disc of the present invention.

[0039]FIG. 12 is a block diagram illustrating an embodiment of anoptical disc drive according to the present invention.

[0040]FIG. 13 shows a sector arrangement on a conventional optical disc.

BEST MODE FOR CARRYING OUT THE INVENTION

[0041] Hereinafter, preferred embodiments of the present invention willbe described with reference to the accompanying drawings.

[0042]FIG. 1(a) illustrates a first embodiment of an optical discaccording to the present invention. As shown in FIG. 1(a), an opticaldisc substrate 101 according to this embodiment is a disklike plate, onthe recording plane of which multiple information tracks (which will beherein referred to as “tracks”) have been formed. Each of these tracksis made up of a plurality of sectors 104, each including a header field102 and a recording field 103. The header field 102 is made up ofembossed pits (pre-pits) that were formed while the disc was beingmanufactured. The arrangement of these pits represents non-rewritableinformation. On the other hand, the recording field 103 is an area onwhich information can be written and rewritten. As shown in FIG. 1(b),the optical disc substrate 101 of this embodiment includes a pluralityof sector groups 105, each being made up of a predetermined number of(e.g., 32 in this embodiment) sectors.

[0043] A state in which a number of tracks are arranged concentricallyis illustrated in FIG. 1(a) for the sake of simplicity. Actually,though, the tracks are arranged spirally in this embodiment.

[0044] The optical disc substrate 101 includes a phase change typerecording film that changes from an amorphous state into a crystallinestate, or vice versa, when exposed to laser radiation. Thus, informationcan be written on, or erased from, the recording film. The informationis read based on a difference in the intensity of the light that hasbeen reflected from respective parts of the optical disc (i.e., based ona difference in reflectance of respective parts of the recording film).

[0045] In this embodiment, the revolution of the optical disc substrate101 is controlled by a ZCLV (zoned constant linear velocity) technique.Accordingly, the information recording plane of the optical discsubstrate 101 is divided into a plurality of zones in the radialdirection thereof. These zones are defined so as to have a substantiallyequal size (i.e., width) as measured in the radial direction. Each ofthese zones includes the same number of tracks. However, the number ofsectors included in one zone (or in a track of the zone) is differentfrom the number of sectors included in another zone (or in a track ofthe zone). That is to say, the number of sectors included in anouter-periphery zone or a track thereof is greater than the number ofsectors included in an inner-periphery zone or a track thereof. Morespecifically, the number of sectors included in each track in one zoneis set greater by one than the number of sectors included in each trackin another zone that is adjacent to the former zone and closer to theinner periphery.

[0046] The number of revolutions of the optical disc substrate 101 iscontrolled at a constant value within the same zone. However, the numberof revolutions differs from one zone to another. Specifically, thenumber of revolutions of the optical disc substrate 101 in anouter-periphery zone is smaller than in an inner-periphery zone.Accordingly, the linear velocity at which a laser beam spot moves on thedisc or the recording linear density is kept substantially constant fordifferent zones.

[0047] Next, the relationship between the sectors 104 and a sector group105 on the optical disc medium of the present invention will bedescribed in further detail with reference to FIG. 2.

[0048] In the optical disc of this embodiment, a track is made up of aplurality of contiguous sector groups 105. Each of these sector groups105 consists of 32 sectors 104 that are continuous with each other onthe track. Each of these sectors 104 includes a header field 102 locatedat the top thereof and a recording field 103 that follows the headerfield 102.

[0049] In the sector 104 located at the top of each sector group 105,the header field 102 thereof has been provided with a sync mark “S” thathas been formed in the shape of pits (i.e., pre-formatted). When thesync mark “S” is detected by a variation in intensity of the lightreflected from the optical disc, the top of the sector group 105 can belocated.

[0050] In each of the 31 sectors 104 that follow the first sector 104 inthe sector group 105, the header field thereof is provided with apositive or negative mark that has also been formed in the shape ofpits. By allocating information bits “1” and “0” to the positive andnegative marks, respectively, each of the sectors 104 included in eachsector group 105 can have one-bit information.

[0051] By pre-arranging the sync mark, positive marks and negative marks(i.e., identification marks) in each sector group 105 in this manner,31-bit information can be recorded on the sector group 105. Furthermore,the 31-bit information is divided into 31 pieces, which are distributedto the 31 sectors 104, respectively.

[0052] In this embodiment, the 31-bit information is divided into 19-bitmain information and 12-bit sub-information, and the 19-bit maininformation is used as the location information of the sector group 105.Then, the locations of 19^(th) power of 2 (=524,288) sector groups 105can be specified by the main information thereof. Accordingly, supposingthe top sector group of the overall optical disc has locationinformation of zero and the following sector groups have locationinformation that increases one by one from zero to represent theabsolute locations of the sector groups 105 by the 19-bit maininformation, 19^(th) power of 2 sector groups 105 can be provided perdisc. Thus, if a single sector 104 has information of 2,048 bytes and asingle sector group 105 has information of 65,536 (=2,048×32) bytes, themaximum amount of data that can be accessed through the 19-bit maininformation is 34 gigabytes.

[0053] On the other hand, an error correction code is allocated to the12-bit sub-information. Even if any bit included in the 19-bit maininformation or the 12-bit sub-information is lost because of a defect orsome other reason or even if information is detected erroneously duringa read operation, the error can be corrected by using this errorcorrection code. For example, this error correction code may be used forall of the information of 31 bits.

[0054] If the location information of the sector groups 105 increasesone by one monotonically along the tracks, the location informationrepresented by the high-order bits of one sector group 105 ispredictable from the location information of the previous sector group105. Accordingly, the low-order 8 bits of the 12-bit sub-information mayalso be used as the error correction code, for example.

[0055] Next, exemplary physical shapes of the header fields 102 will bedescribed with reference to FIGS. 3(a) and 3(b).

[0056]FIG. 3(a) illustrates an exemplary shape of a sync mark. This syncmark consists of a single pit having a length of 16T, where “1” is areference clock period for recording. A length on the optical disc maybe represented as a multiple of the distance that a light beam goes inone reference clock period (T). Accordingly, a pit having a length of16T means a pit having a size corresponding to 16×T, which is a time ittakes for a light spot formed on the rotating optical disc to move fromone end of the pit to the other on the track.

[0057]FIG. 3(b) illustrates an exemplary shape for a positive mark. Thispositive mark is made up of a pit having a length of 8T and another pitthat has been formed so as to be spaced apart from the former pit by 4Tand that has a length of 4T.

[0058]FIG. 3(c) illustrates an exemplary shape for a negative mark. Thisnegative mark is made up of a pit having a length of 4T and another pitthat has been formed so as to be spaced apart from the former pit by 4Tand that has a length of 8T.

[0059] In reading out location information, when a pit that issufficiently longer than any of the pits included in the positive andnegative marks (e.g., a pit having a length equal to or greater thanthat of a pit having an intermediate length (e.g., 12T) between thelength (8T) of the longest pit in the positive and negative marks andthe length of 16T of the sync mark pit) has been detected, then the markdetected may be specified as the sync mark shown in FIG. 3(a).

[0060] Also, where two pits having respective lengths of less than 12Thave been detected consecutively, these two pits should be identified asthe longer pit and the shorter pit. If the longer pit has been detectedbefore the shorter pit, then the mark detected may be specified as thepositive mark shown in FIG. 3(b). Conversely, if the shorter pit hasbeen detected before the longer pit, then the mark detected may bespecified as the negative mark shown in FIG. 3(c).

[0061] Alternatively, four detection windows may be provided on a 4Tbasis and the signals, detected at the respective centers of thesedetection windows, may be digitized. In that case, the marks detectedmay be specified by the digitized signals in the following manner.Specifically, if the digitized signals are “1111”, then the markdetected may be specified as a sync mark. If the digitized signals are“1101”, then the mark detected may be specified as a positive mark. Ifthe digitized signals are “1011”, then the mark detected may bespecified as a negative mark. And if the digitized signals are none ofthese, then the mark detected may be regarded as an error.

[0062] According to these detection methods, there is no need to detectthe absolute length every clock period although that detection isusually needed in reading out a data signal. Thus, the PLL does not haveto lock onto a signal representing location information. As a result,the redundancy normally caused by a VFO and so on can be saved.

[0063] In this manner, the information recorded on each header field 102of this embodiment is represented by a small number of pits as shown inFIGS. 3(a) through 3(c). For this reason, there is no need to lock thePLL for any header field. Accordingly, in reading multiple sectorsconsecutively, if the PLL is once locked in the recording field of apreceding sector and then kept locked even after a succeeding sector hasbeen entered, then the state of the PLL in the preceding sector can alsobe held even in the recording field of the succeeding sector. Thus, thePLL does not have to be locked all over again, and the VFO area may beomitted from the recording field or the length thereof may be minimized.To eliminate the VFO areas from the recording fields in this manner, thespace (i.e., the header gap) between the preceding and succeedingrecording fields should have a length at most equivalent to the responsetime of the PLL. In this embodiment, the response time of the PLL isabout 200T.

[0064] Next, exemplary arrangements of the sync marks, positive marksand negative marks (which will be herein referred to simply as“identification marks” collectively) on the optical disc will bedescribed with reference to FIGS. 4(a) through 4(d).

[0065] Suppose the optical disc substrate 101 is an optical disc of aland/groove recording type, which includes both wobbling lands (orgroove portions) and grooves (or inter-groove portions) as its tracksand on which information can be recorded on both the lands and grooves.In that case, as shown in FIG. 4(a), for example, the identificationmarks may be arranged between the lands (or groove portions) and grooves(or inter-groove portions) so as to be on the tracks but shifted fromthe respective centers of the tracks by one half track pitch. In such anarrangement, by reference to a signal level balance between anidentification mark on the disc inner periphery and anotheridentification mark on the disc outer periphery, it is possible todetect how much the light beam following the tracks is shifted from thecenters thereof, and correct the shift, on a sector-by-sector basis.

[0066] Alternatively, if no such correction is needed, then thoseidentification marks may also be arranged on the track centerlines ofthe lands and grooves as shown in FIG. 4(b).

[0067] Also, to prevent any interference from occurring between adjacentidentification marks, the identification marks may be alternatelyarranged on the lands and on the grooves so as to be shifted from eachother as shown in FIG. 4(c).

[0068] On the other hand, the optical disc substrate 101 may be anoptical disc of the type recording information only on the lands or onlyon the grooves. For example, supposing information should be recordedonly on the grooves (or inter-groove portions), the identification marksmay be arranged only on the inter-groove portions, or the tracks onwhich the information is recorded, as shown in FIG. 4(d).

[0069] According to this embodiment, to access a particular sector in asector group, first, a given sector group is identified by detecting thelocation information of the sector group. In this manner, the sectorgroup including the target sector can be accessed. Next, the sectors ofthat sector group are counted one by one from the top sector thereof,thereby accessing the target sector.

[0070] In the embodiment described above, the identification mark isdisposed at the beginning of each sector. However, the identificationmark does not have to be detected at the beginning of each sector.Alternatively, the identification mark may be disposed at the end ofeach sector, for example.

[0071] As described above, in the optical disc of this embodiment, eachsector group is made up of a predetermined number of (a plurality of)sectors, and the location information of each sector group is dividedand distributed to the respective sectors of the sector group. Theidentification marks, representing the location information of eachsector group, are arranged dispersively and periodically only withinrelatively short areas (having a length of 20T or less) between therecording fields of adjacent sectors. In this manner, the overhead canbe reduced, and the adverse effects of local loss resulting fromdefects, for example, can be minimized, thereby increasing thereliability. More specifically, in the conventional example illustratedin FIG. 13, the area on which user data cannot be written (i.e., theoverhead) accounts for as much as 5% of the overall area of the tracks.In contrast, according to this embodiment, the overhead can be reducedto as low as about 1% of the overall track area.

[0072] It should be noted that the location information of each sectorgroup does not have to be distributed to a plurality of sectors thatmakes up the same sector group. For example, the location information ofeach sector group may also be distributed to a plurality of sectors thatmakes up another sector group, which is located on the same track towhich the former sector group belongs. This point will be described infurther detail later with reference to FIGS. 5 and 11.

Exemplary Zone Arrangement 1

[0073] An exemplary zone-by-zone arrangement for an optical discaccording to the present invention is shown in the following Table 1:TABLE 1 Number of Number of Number of Zone sectors Number of Number ofSector Remainder No. per track Tracks Sectors groups Sectors 0 19 1,88835,872 1,121 0 1 20 1,888 37,760 1,180 0 2 21 1,888 39,648 1,239 0 3 221,888 41,536 1,298 0 4 23 1,888 43,424 1,357 0 5 24 1,888 45,312 1,416 06 25 1,888 47,200 1,475 0 7 26 1,888 49,088 1,534 0 8 27 1,888 50,9761,593 0 9 28 1,888 52,864 1,652 0 10 29 1,888 54,752 1,711 0 11 30 1,88856,640 1,770 0 12 31 1,888 58,528 1,829 0 13 32 1,888 60,416 1,888 0 1433 1,888 62,304 1,947 0 15 34 1,888 64,192 2,006 0 16 35 1,888 66,0802,065 0 17 36 1,888 67,968 2,124 0 18 37 1,888 69,856 2,183 0 19 381,888 71,744 2,242 0 20 39 1,888 73,632 2,301 0 21 40 1,888 75,520 2,3600 22 41 1,888 77,408 2,419 0 23 42 1,888 79,296 2,478 0

[0074] In the example shown in Table 1, the number of sectors that makesup each zone is (the number odf sectors per track)×(the number oftrachs). The number of sector groups is the quotient given by (thenumber of sectors)÷(the number of sectors that makes up each sectorgroup). On the other hand, the number of remainder sectors, which areextra sectors that do not make up any sector group, is obtained as theremainder of (the number of sectors)÷(the number of sectors that makesup each sector group). In this case, the remainder sectors that do notmake up any sector group have no location information and the absolutelocations thereof are non-specifiable. Thus, the remainder sectors arenot used to record information thereon.

[0075] As shown in Table 1, the number of tracks included is the same ineach and every zone on the optical disc of this embodiment.Specifically, 1,888 tracks belong to each and every zone. Supposing thenumber of sectors per track in a zone is n, the number of sectors thatmakes up that zone is 1,888×n, which is a multiple of the number ofsectors of “32” that makes up each sector group. That is to say, in thisembodiment, the number of sectors that makes up each zone is a multipleof the number of sectors that makes up each sector group, and the numberof remainder sectors that do not make up any sector group is zero. Thus,each and every sector in a zone can be used without leaving any extrasector.

Exemplary Arrangement 1 of the Location Information of a Sector Group

[0076] An exemplary arrangement of the location information in a sectorgroup on the optical disc of the present invention will be describedmore specifically with reference to FIG. 5. In the example shown in FIG.5, a sync mark “S” is provided for the top sector among a plurality ofsectors that makes up the sector group 105 specified by an address“123456”. The internal arrangement of any other sector group 105 havinga different address is the same as that of the sector group 105specified by the address “123456”.

[0077] As shown in the lower part of FIG. 5, the 31 sectors that followthe top sector include the location information of the sector group 105to which those sectors belong. This location information is representedby the identification marks of 31 bits b0 through b30. That is to say,the 31-bit identification marks have the location information “123456”.

[0078] In the same way, in the sector group 105 specified by an address“123457”, the location information “123457” is recorded dispersively onthe 31 sectors 104 that make up the sector group 105.

[0079] In this manner, in the example shown in FIG. 5, the address g ofeach sector group is specified by the identification marks that aredistributed to a plurality of sectors that makes up the same sectorgroup. On the other hand, in another exemplary location informationarrangement to be described later with reference to FIG. 11, thelocation information of each sector group is distributed to a pluralityof sectors that are included in the previous sector group on the sametrack. The advantages and disadvantages of these two exemplaryarrangements will be mentioned after the arrangement shown in FIG. 11has been described.

Buffer Track

[0080] A zone boundary area on the optical disc of the present inventionwill be described with reference to FIGS. 6(a) and 6(b).

[0081]FIG. 6(a) shows some of the tracks in and between Zones Nos. 0 and1. Specifically, the reference numeral 701 denotes the last trackbelonging to Zone No. 0, the reference numerals 702 and 703 denotebuffer tracks and the reference numeral 704 denote the first trackbelonging to Zone No. 1. FIG. 6(b) shows the arrangement of the buffertrack 702 shown in FIG. 6(a).

[0082] Since Zones Nos. 0 and 1 have mutually different numbers ofsectors per track, the sector arrangement angles are different from eachother in the zone boundary area. As a result, interference might occurbetween a header field in one track and a recording field in anotheradjacent track. To prevent this interference, the buffer tracks 702 and703 are sometimes provided between the zones as shown in FIG. 6(a). Thebuffer tracks 702 and 703 belong to neither Zone No. 0 nor Zone No. 1and are non-usable dummy tracks.

[0083] In this embodiment, the header field of each of the sectors thatmake up the buffer tracks 702 and 703 as dummy tracks is provided withan invalidity mark “I”, thereby distinguishing these dummy sectors fromsectors on the tracks having valid information thereon.

[0084] Suppose a light beam spot is now moving from Zone No. 0 into ZoneNo. 1 during a write, read or standby mode. In this case, first, thelight beam spot moves from the last track 701 of Zone No. 0 to enter adummy sector as one of the sectors making up the buffer track 702. Next,when the invalidity mark is detected from the header field of the dummysector on the buffer track 702, that sector is regarded as a dummysector. Then, processing of moving into Zone No. 1 is performed so thatthe light beam spot can move into the first track 704 of Zone No. 1quickly.

[0085] Furthermore, if the buffer track 702 or 703 is tracked during aseek mode, then the track is recognizable as a dummy track just bydetecting the header field of one sector, not by detecting 32 sectors asneeded to detect the location information of a sector group.Accordingly, the next processing can be started very quickly.

[0086] The invalidity mark “I” may be formed like the sync mark shown inFIG. 3(a), for example. In that case, a given sector is not identifiableas a dummy sector by itself. However, as soon as the same sync mark isdetected from two consecutive sectors, those sectors may be identifiedas dummy sectors. By providing the invalidity mark for the dummy sectorsin this manner, the access performance is improvable.

Logical Processing Block

[0087] In recording information on an optical disc, normally somelogical processing is performed. For example, an error correction codeis added to correct an error occurring during a read or write operation.Or to prevent errors from being caused locally in a particular part,interleaving processing is performed by rearranging the code sequences.When such an error correction code is added or when such interleaving isperformed, the processing may be carried out using a predeterminednumber of sectors as one block.

[0088] The relationship between the sector groups and the logicalprocessing blocks on an optical disc will be described with reference toFIGS. 7(a) and 7(b). FIG. 7(a) shows a relationship between the sectorgroups and error correcting blocks, while FIG. 7(b) shows a relationshipbetween the sector groups and interleaving blocks. In FIG. 7(a), thereference numeral 801 denotes the error correcting blocks. In FIG. 7(b),the reference numeral 802 denotes the interleaving blocks.

[0089] In writing and/or reading information on/from the optical disc ofthe present invention, the error correction and interleaving may becarried out on a 16 sector basis. On the other hand, each sector group105 is made up of 32 sectors in this embodiment. That is to say, thenumber of sectors of “32” that makes up one sector group 105 is amultiple of the number of sectors of “16” that makes up one errorcorrecting or interleaving block 801 or 802. Furthermore, in the opticaldisc of this embodiment, the start sector of each sector group 105 isthe start sector of the error correcting block 801 or the interleavingblock 802.

[0090] In actually writing or reading information, the locationinformation is obtained only on a sector group basis. Accordingly, evenif just a portion of one sector group 105 needs to be read, that sectorgroup should be read entirely and the location information of thatsector group should be acquired. For example, if the number of sectorsthat makes up one sector group 105 were not correlated to the errorcorrecting block 801 or interleaving block 802, then the logicalprocessing such as error correction or interleaving should be carriedout on multiple sector groups 105.

[0091] According to this embodiment, however, the number of sectors thatmakes up one sector group is a multiple of the number of sectors thatmakes up one error correcting or interleaving block. In addition, thestart sector of each sector group is identical with the start sector ofeach error correcting or interleaving block. Thus, the performance ofthe error correction or interleaving processing is improvable.

Replacement Processing

[0092] A method for performing replacement processing on the opticaldisc of the present invention will be described with reference to FIG.8.

[0093] User data is sequentially written on the optical disc whiledetecting the location information of the sector groups. Once the userdata has been written on a user area, verify processing (i.e., writeverify) is carried out to see if the data has been written successfully.In normal verify processing, if errors have occurred in an errorcorrecting block at less than a predetermined error rate, then the datawritten is verified and the next processing is started. However, ifthere are any defects on the disc and if errors have occurred in anerror correcting block at the predetermined error rate or more, then theblock is regarded as defective and replacement processing is carriedout.

[0094] In this embodiment, each zone includes a user area and a sparearea as shown in FIG. 8. User data is written on the user area, whileuser data, which should have been written in a part of the user areaon/from which the data has been once written or read but which has beendetected as defective, is written on the spare area.

[0095] For example, the user area may include sector groups 105specified by addresses “0” through “999”, while the spare area mayinclude spare sector groups 901 specified by addresses “1000” through“1128”.

[0096] Suppose when user data is written on a sector group 105 specifiedby an address “500” and then subjected to verify processing, the lattersecond error correcting block, included in the two error correctingblocks associated with the sector group, is regarded as a defectiveblock. In that case, the former first error correcting block and thesecond error correcting block are both replaced with one spare sectorgroup 901 specified by an address “1000”, and the sector group 105specified by the address “500” is also replaced with the same sparesector group 901 specified by the address “1000”. This replacement isregistered in a replacement list. Optionally, information about thereplacement of the first and second error correcting blocks associatedwith the sector group 105 specified by the address “500” may beregistered in the list.

[0097] In a read operation on the other hand, the sector groups aresequentially read one after another. Specifically, when a sector group105 specified by an address “499” has been read, the next sector groupto be read will be the spare sector group 901 specified by the address“1000” in accordance with the information that has been registered inthe replacement list. When the spare sector group 901 specified by theaddress “1000” has been read, a sector group 105 specified by an address“501” will be read next.

[0098] In this manner, according to this embodiment, the replacementprocessing is carried out on a sector group basis. Thus, while sectorgroups are being read, the alternate sector group can start being readquickly without detecting the location information of the originalsector group that has been replaced with the alternate sector group. Asa result, the replacement processing can be performed at a higherprocessing speed.

Sector Location Information in Recording Field

[0099] Another embodiment of an optical disc according to the presentinvention will be described with reference to FIG. 9. In thisembodiment, sector location information 1001, representing the locationof a sector, is provided within the recording field 103, not within theheader field 102. When information such as user data is written on therecording field 103, the sector location information 1001 is recorded atthe top of the main information. In this manner, if the sector locationinformation 1001 is recorded at the top of the information to berecorded on the recording field 103, then no VFO area and other areasare needed to read the sector location information 1001. As a result,the degree of redundancy can be reduced.

[0100] As the sector location information 1001, information defined by(the location information of a sector group)×32+(a sector number in thesector group) may be selected, for example. Alternatively, the sectorlocation information 1001 may also be a logical address different fromthe location information of its sector group, for example. As usedherein, the “logical address” is an address to be read by an apparatus(e.g., host computer) which is located at a higher level than theoptical disc drive.

[0101] In this embodiment, when a recorded part is sought, the sectorlocation information 1001 is detected before the location information ofits sector group 105 is detected from the 32 sectors of the sector group105. Then, just by reading at least one sector, the absolute location ofthe sector can be specified. Furthermore, when operation processing isperformed after that, the location information of its sector group canalso be confirmed.

[0102] In this manner, the location information of each sector isrecorded, along with the information to be written, on the optical discof this embodiment, thus improving the access performance.

Exemplary Zone Arrangement 2

[0103] Another exemplary zone arrangement for an optical disc accordingto the present invention will be described with reference to thefollowing Table 2: TABLE 2 Number of Number of Number of Zone sectorsNumber of Number of Sector Remainder No. per track Tracks Sectors Groupssectors 0 19 1,900 36,100 1,128 4 1 20 1,900 38,000 1,187 16 2 21 1,90039,900 1,246 28 3 22 1,900 41,800 1,306 8 4 23 1,900 43,700 1,365 20 524 1,900 45,600 1,425 0 6 25 1,900 47,500 1,484 12 7 26 1,900 49,4001,543 24 8 27 1,900 51,300 1,603 4 9 28 1,900 53,200 1,662 16 10 291,900 55,100 1,721 28 11 30 1,900 57,000 1,781 8 12 31 1,900 58,9001,840 20 13 32 1,900 60,800 1,900 0 14 33 1,900 62,700 1,959 12 15 341,900 64,600 2,018 24 16 35 1,900 66,500 2,078 4 17 36 1,900 68,4002,137 16 18 37 1,900 70,300 2,196 28 19 38 1,900 72,200 2,256 8 20 391,900 74,100 2,315 20 21 40 1,900 76,000 2,375 0 22 41 1,900 77,9002,434 12 23 42 1,900 79,800 2,493 24

[0104] In the optical disc zone arrangement that has already beendescribed with reference to Table 1, the number of sectors that makes upeach zone is a multiple of the number of sectors that makes up onesector group. Thus, the zone arrangement has a low degree offlexibility. In contrast, in the zone arrangement shown in Table 2, thenumber of sectors that makes up each zone is not a multiple of thenumber of sectors that makes up one sector group. In this exemplary zonearrangement, the number of tracks is determined by a track pitch thatenables the optical disc to exhibit its highest recording performance,and the number of sectors per zone is determined by the number oftracks. Accordingly, there are some zones that include remainder sectorsbelonging to no sector groups.

[0105]FIG. 10 shows the end of Zone No. 0 on an optical disc having sucha zone arrangement to a larger scale. Zone No. 0 consists of 1,128sector groups 105 specified by addresses “0” through “1127” and fournon-used remainder sectors 1201.

[0106] Each sector 104 in each sector group 105 includes validinformation in its header field. On the other hand, each remaindersector 1201 has an invalidity mark “I” in its header field. Thus, eachremainder sector 1201 is distinguished from each sector 104 includingvalid information.

[0107] In writing user data, for example, after the data has beenwritten on the sector group 105 specified by the address “1127”, thelight beam spot enters the remainder sectors 1201. As the invaliditymarks provided for the remainder sectors 1201 are detected at this time,the remainder sectors 1201 are skipped. As a result, no data is writtenon the remainder sectors and the light beam spot moves into Zone No. 1.

[0108] Alternatively, to detect the remainder sector 1201 moreaccurately, an invalidity signal may be recorded on the remainder sector1201 without skipping the remainder sector 1201. In that case, when theinvalidity signal is detected from the recording field 103, the sectorin question is identifiable as the remainder sector 1201. As theinvalidity signal to be written on the recording field of the remaindersector 1201, a pattern that does not exist in a modulation code ispreferably used. For example, if the modulation code adopted is aneight-to-sixteen modulation code sequence, a continuous pattern of 14Tmay be recorded as the invalidity signal.

[0109] The invalidity mark “I” may be formed as the sync mark shown inFIG. 3(a). In that case, a given sector is not identifiable as aremainder sector by itself. However, if the same sync mark is detectedfrom two consecutive sectors, then those sectors may be regarded asremainder sectors 1201.

[0110] As described above, in at least one zone, the number of sectorsthat makes up the zone is not a multiple of the number of sectors thatmakes up one sector group and the zone is provided with an appropriatenumber of remainder sectors when needed. Then, the disc can be designedmore flexibly. Also, by providing an invalidity header for eachremainder sector, the access performance is improvable. In addition, byrecording no information on any remainder sector, the processing speedcan be further increased. Optionally, when an invalidity signal isrecorded on each remainder sector, the remainder sector can be detectedmore accurately.

Exemplary Arrangement 2 of the Location Information of a Sector Group

[0111] Another exemplary arrangement of the location information of asector group on the optical disc of the present invention will bedescribed with reference to FIG. 11.

[0112] An optical disc having the exemplary arrangement shown in FIG. 5is compliant with a format in which the location information of a sectorgroup is distributed within the same sector group. In that case,however, to detect the location information of a sector group, aplurality of sectors included in that sector group should be read, thusresulting in a low processing speed.

[0113] In the optical disc of this embodiment, the location informationof each sector group is arranged differently from the example shown inFIG. 5. In the other respects, however, the optical disc of thisembodiment is the same as the optical disc described above.

[0114] In FIG. 11, a sync mark “S” is provided for the first one of aplurality of sectors that makes up the sector group 105 specified by anaddress “123456”, for example. However, the 31 sectors that follow thefirst sector do not include the location information of the sector group105 to which those sectors belong but the location information “123457”of its succeeding sector group 105.

[0115] In the same way, as for the sector group 105 specified by anaddress “123457”, location information “123458” is recorded dispersivelyon the 31 sectors 104 that makes up the sector group 105.

[0116] In this manner, a sector group specified by an address “G”includes location information “G+1” on the header fields of the sectorsthat makes up the sector group.

[0117] In such an arrangement, in reading the location information fromthe sector group 105 specified by the address “123456”, the locationinformation of the sector group 105 specified by the address “123457”will have been read at the header field 102 of the last sector of thesector group 105 specified by the address “123456”. That is to say,before the sector group 105 specified by the address “123457” isreached, the location information “123457” will have been read.Accordingly, before a sector group is reached, the location informationof that sector group can be detected, thus realizing quick processing.

[0118] However, if the location information of each sector group isdistributed to a plurality of sectors included in the previous sectorgroup on the same track, then the sectors, on which the locationinformation of a sector group located at the top of each zone should berecorded, cannot be found at appropriate locations. As a result, such asector group located at the top of each zone cannot be used to writeuser data or any other type of data thereon.

[0119] In contrast, in the example shown in FIG. 5, each and everysector group within a zone includes its own location information, andtherefore, the sector groups within one zone can be all used.

Optical Disc Drive

[0120]FIG. 12 illustrates an embodiment of an optical disc recorderaccording to the present invention. This optical disc recorder issuitably applicable for use to write and/or read information on/from theoptical disc of the present invention described above.

[0121] This optical disc recorder includes: an optical head 1401 forfocusing a laser beam on a track of an optical disc 101; a circuit A fordetecting a sector location, to which the laser beam is irradiated, onthe track by processing the output signal of the optical head 1401; anda circuit B for generating a recording signal based on the informationto be written on the optical disc 101.

[0122] The optical head 1401 includes an element for performingelectro-optical conversion to write information on a recording field ofthe optical disc 101 or to read information from a header field or arecording field of the optical disc 101. The optical head 1401 makes alight beam follow the tracks on the optical disc 101, receives the lightthat has been reflected from the optical disc 101 and reads and outputsa required signal based on the reflected light.

[0123] In accordance with an optical signal that has been output fromthe optical head 1401, the circuit A reads the location information of asector from the optical disc 101. More specifically, the circuit Aincludes header detecting means 1402, sector group location informationdetecting means 1403, sector detecting means 1404 and sector locationinformation computing means 1405. In response to the output signal ofthe optical head 1401, the header detecting means 1402 detects andidentifies the header field of the sector irradiated with the lightbeam. The sector group location information detecting means 1403 detectsthe location information of the sector group based on the output of theheader detecting means 1402. In accordance with the output of the headerdetecting means 1402, the sector detecting means 1404 detects and countsthe sectors in the sector group, thereby outputting the number of theparticular sector in the sector group. The sector location informationcomputing means 1405 obtains the location information of the sector inquestion by performing computation on the output of the sector grouplocation information detecting means 1403 and on the output of thesector detecting means 1404.

[0124] The circuit B includes signal outputting means 1406, recordingsignal generating means 1407 and recording signal processing means 1408.The signal outputting means 1406 outputs user data and a signal such asan invalidity signal. In accordance with the outputs of the sectorlocation information computing means 1405 and signal outputting means1406, the recording signal generating means 1407 generates a recordingsignal. And the recording signal processing means 1408 converts theoutput signal of the recording signal generating means 1407 into arecording laser signal.

[0125] Hereinafter, it will be described how to record information onthe optical disc of the present invention by using this optical discrecorder.

[0126] First, it will be described how to write data on the optical discthat has already been described with reference to FIG. 9. Then, thesector location information computing means 1405 obtains and outputs thesector location information based on the sector group locationinformation that has been output from the sector group locationinformation detecting means 1403 and the sector number in the sectorgroup that has been output from the sector detecting means 1404. In thiscase, the sector location information is defined by (sector grouplocation information)×32+(the sector number in the sector group).

[0127] Next, the recording signal generating means 1407 adds thesector-by-sector data, which has been supplied from the signaloutputting means 1406, to the sector location information and thensubjects it to various types of processing, including modulation (e.g.,eight-to-sixteen modulation) and the addition of SYNC (synchronizationcode), thereby generating and outputting a recording signal. Inaccordance with the output signal of the recording signal generatingmeans 1407, information is recorded on the optical disc 101 by way ofthe recording signal processing means 1408.

[0128] Next, it will be described how to write data on the optical discincluding the remainder sectors 1201 shown in FIG. 10. The optical discused may be of a type recording no signals on any of the remaindersectors 1201. In that case, when the sector group location informationdetecting means 1403 detects an invalidity mark, the recording signalprocessing means 1408 operates in such a manner as to output norecording laser signals. On the other hand, the optical disc used mayalso be of the type recording an invalidity signal on each of theremainder sectors 1201. In such a situation, when the sector grouplocation information detecting means 1403 detects an invalidity mark,the signal outputting means 1406 outputs an invalidity signal as thesector data. As a result, the invalidity signal is recorded on theoptical disc.

[0129] In this manner, the optical disc recorder of this embodiment canappropriately record information on any of the various types of opticaldiscs according to the present invention.

Industrial Applicability

[0130] In the optical disc of the present invention, a sector group ismade up of a predetermined number of sectors, the location informationof the sector group is divided into multiple pieces each including apredetermined amount of information, and the location information isdistributed to the multiple sectors in the sector group. Thus, theoverhead can be reduced and the unwanted effects of local loss due todefects, for example, can also be reduced. As a result, the locationinformation can be detected much more reliably.

[0131] Also, according to the recording method of the present invention,when recording is performed on the optical disc, replacement processingis carried out on the basis of a sector group, which constitutes aminimum unit representing the location information. Thus, thereplacement processing can be performed at a higher processing speed.

[0132] In an embodiment where the location information of each sector ofthe optical disc is recorded on that sector along with the informationto be written thereon, that sector can be read without detecting thelocation information of its sector group. Then, the absolute location ofthe sector can be specified quickly and the access performance isimprovable. Furthermore, in an embodiment where recording is performedon the optical disc including remainder sectors, no information may berecorded on any of the remainder sectors and the next processing may bestarted immediately. Then, the processing speed can be increased.

[0133] Also, in another embodiment where recording is performed on theoptical disc including the remainder sectors, an invalidity signal maybe recorded on each of those remainder sectors. In that case, when theinvalidity signal is detected during a read operation, the given sectoris identifiable as a remainder sector. Since the remainder sector canalso be detected by an identification mark, the remainder sector isdetectible even more accurately.

[0134] In an optical disc recorder according to the present invention,where the location information of each sector is recorded on that sectoralong with the information to be written thereon, that sector can beread without detecting the location information of its sector group.Then, the absolute location of the sector can be specified and theaccess performance is improvable. In an embodiment where recording isperformed on the optical disc including remainder sectors, noinformation may be recorded on any of the remainder sectors and the nextprocessing may be started immediately. Then, the processing speed can beincreased. Alternatively, an invalidity signal may be recorded on eachof those remainder sectors. In that case, when the invalidity signal isdetected during a read operation, the given sector is identifiable as aremainder sector. Since the remainder sector can also be detected by anidentification mark, the remainder sector is detectible even moreaccurately.

1. An optical disc medium comprising a plurality of sector groups, eachsaid sector group being made up of multiple sectors that are contiguouswith each other in a circumferential direction on a track, wherein in atleast some of the sector groups, the location information thereof isdivided into multiple pieces of information and distributed toassociated ones of the sectors on the same track.
 2. The optical discmedium of claim 1, wherein the location information is represented by aplurality of identification marks that are formed as embossed pits. 3.The optical disc medium of claim 2, wherein each said embossed pit isformed between recording fields of associated ones of the sectors thatare adjacent to each other in the circumferential direction on thetrack.
 4. The optical disc medium of one of claims 1 to 3, wherein thesectors included in each said sector group are 32 contiguous sectors. 5.The optical disc medium of one of claims 1 to 4, wherein each saididentification mark assumes one of three mutually different states andrepresents synchronization information or one-bit information of 1 or 0by any of the three different states.
 6. The optical disc medium of oneof claims 1 to 5, wherein each said identification mark is providedwithin a header gap that has a length of 200T or less in a direction inwhich the track extends, where T is a distance that a light beam goes inone reference clock period.
 7. The optical disc medium of one of claims1 to 6, wherein each said identification mark is made up of at most twoof the embossed pits.
 8. The optical disc medium of one of claims 1 to7, wherein the identification marks are arranged on a centerline of thetrack on which information is recorded.
 9. The optical disc medium ofone of claims 1 to 7, wherein the identification marks are arranged soas to be shifted by a half track pitch from a centerline of the track onwhich information is recorded.
 10. The optical disc medium of one ofclaims 1 to 9, wherein the optical disc medium has a recording planethat is divided into a plurality of band-like zones, the zones beingarranged concentrically around the center of the disc medium, andwherein multiple tracks are included in each said zone, the number ofsectors included in each said track changing on a zone-by-zone basis,and wherein the number of sectors included in each said zone is amultiple of the number of sectors that makes up each said sector group.11. The optical disc medium of one of claims 1 to 9, wherein thelocation information of an arbitrary one of the sector groups isdistributed to multiple sectors included in the sector group.
 12. Theoptical disc medium of one of claims 1 to 9, wherein the optical discmedium comprises a non-usable dummy sector, and wherein theidentification mark included in the dummy sector is provided withinvalidity information that makes the sector identifiable as the dummysector.
 13. The optical disc medium of claim 12, wherein the invalidityinformation is identical with the synchronization information.
 14. Theoptical disc medium of one of claims 1 to 9, wherein the number ofsectors that makes up each said sector group is a multiple of the numberof sectors that makes up a sector block on which logical processing isperformed.
 15. The optical disc medium of claim 14, wherein the sectorlocated at the top of each said sector group is identical with thesector located at the top of one of the sector blocks on which thelogical processing is performed.
 16. The optical disc medium of claim 14or 15, wherein the logical processing is error correction processing.17. The optical disc medium of claim 14 or 15, wherein the logicalprocessing is interleaving processing.
 18. The optical disc medium ofone of claims 1 to 9, wherein replacement processing is performed on asector group basis.
 19. An optical disc recording method for performingrecording on the optical disc medium as recited in one of claims 1 to 9,wherein replacement processing is performed on a sector group basis. 20.The optical disc medium of one of claims 1 to 9, wherein each saidsector has its location information recorded thereon.
 21. An opticaldisc recording method for performing recording on the optical discmedium as recited in one of claims 1 to 9, wherein each said sector hasits location information recorded thereon.
 22. An optical disc recorderfor performing recording on the optical disc medium as recited in one ofclaims 1 to 9, wherein each said sector has its location informationrecorded thereon.
 23. The optical disc medium of one of claims 1 to 9,wherein the optical disc medium has a recording plane that is dividedinto a plurality of band-like zones, the zones being arrangedconcentrically around the center of the disc medium, and whereinmultiple tracks are included in each said zone, the number of sectorsincluded in each said track changing on a zone-by-zone basis, andwherein in at least one of the zones, the number of sectors that makesup the zone is not a multiple of the number of sectors that makes upeach said sector group.
 24. The optical disc medium of claim 23, whereinthe sectors that make up the zone include a remainder sector that doesnot belong to any of the sector groups, and wherein the identificationmark of the remainder sector is provided with information that makes thesector identifiable as the remainder sector.
 25. The optical disc mediumof claim 23, wherein no information is recorded on the recording fieldof the remainder sector.
 26. An optical disc recording method forrecording information on the optical disc medium of claim 23, whereinthe information is not recorded on the recording field of the remaindersector.
 27. An optical disc recorder for recording information on theoptical disc medium of claim 23, wherein the information is not recordedon the recording field of the remainder sector.
 28. The optical discmedium of claim 23, wherein an invalidity signal is recorded on therecording field of the remainder sector to make the sector identifiableas the remainder sector.
 29. An optical disc recording method forrecording information on the optical disc medium of claim 23, wherein aninvalidity signal is recorded on the remainder sector.
 30. An opticaldisc recorder for recording information on the optical disc medium ofclaim 23, wherein an invalidity signal is recorded on the remaindersector.
 31. The optical disc medium of one of claims 1 to 9, wherein thelocation information that is distributed to the multiple sectors thatmakes up one of the sector groups is the location information of anotherone of the sector groups that is located behind the former sector group.